1. Field of the Invention
This invention relates to a cleaning system for a carding machine, and in particular to a card waste management system for use with a carding machine. One
2. Present State of the Art
One function of the carding process is to remove as much trash and dust from the feedstock as possible in order that the sliver resulting from the carding process will be as clean as possible and can be spun into a yarn of correspondingly high quality. There are many regions on the conventional carding machine where cleaning is effected. One of these is on the lower arc of the takerin as feedstock is transferred on that roller from the feed plate to the main carding cylinder. The usual cleaning arrangement in this region of the carding machine is the mounting of one or more mote knives adjacent to the lower arc of the takerin. Mote knives are effective in removing a certain amount of trash and dust from the feedstock carried by the takerin.
One particularly effective mote plate type of cleaning mechanism for a carding machine is disclosed in EP-B-248649 in the name Carding Specialists (Canada) Limited, and to which reference is directed. The disclosure in EP-248649 is incorporated herein by this reference.
For a fuller disclosure of the inventive mote plate cleaning mechanism described and claimed in this European patent, reference should be had to the full copy of the text. However, brief description will be made below of a preferred embodiment of the mote plate arrangement disclosed in EP-248649, to form background and to assist the description and definition of examples of improved cleaning system for a carding machine, and card waste management system which is the subject of the present patent application. Reference will therefore now be made to FIGS. 1, 2 and 2A of the accompanying drawings, which comprise:
FIG. 1 is a schematic side elevation of the feed region of a conventional carding machine, and illustrates a known mote knife arrangement; and,
FIG. 2 is a side elevation of part of the feed region of a carding machine showing a mote knife cleaning system which forms the subject of EP-248649.
Referring to FIG. 1, there is shown part of a prior art carding machine having a chute feed arrangement 1, a feed plate 2, a feed roller 3 cooperating with the feed plate, a takerin 4, a main carding cylinder 5 and a set of rotating flats 6. The feed roller conveys feed stock from the feed plate 2 to the main carding cylinder 5 along the lower arc of the takerin, and positioned adjacent to this lower arc there are two mote knives 7. A takerin screen 8 is mounted in the region between the takerin and the main carding cylinder, and abuts a cylinder screen 9. It will be seen that each of the mote knives 7 extends substantially diametrically of the takerin and terminates in a free edge that is substantially at right angles to the direction of rotation of the takerin. The mote knives act to divert trash and dust from the fibres carried by the takerin, but their efficiency is generally recognised as being limited, and they are also prone to removing lint and short fibre that could advantageously be incorporated into the finally carded web.
FIGS. 2 and 2A show part of a carding machine similar to that shown in FIG. 1, but modified in accordance with a first embodiment of the invention which is the subject of EP-248649. In this embodiment, the mote knives are replaced by a substantially rigid, flat plate 10 which extends across the full width of the takerin 4a, downstream of the feed roller 3a, and which terminates in a leading edge 11 that is substantially parallel to the axis of the takerin and that faces into the direction of rotation of the takerin. The plate may suitably be metal sheeting, the sheeting having a thickness t of from 1 to 3 mm, with 1.5875 mm sheet presently preferred. The plate is supported by a support bar 12 which extends the full width of the carding machine and is mounted between the side frame members of the carding machine. The plate is followed in the downstream direction by a takerin screen 13, extending to the region of cooperation between the takerin and the main carding cylinder 5a. The leading edge 11 of the plate is spaced from the tips of the teeth on the takerin by a distance x of not more than 5 mm, and preferably in the range 0.25 to 5.00 mm; and the plate lies in a plane that makes an angle of from 70.degree. to 120.degree. to a plane A--A radial of the takerin and intersecting the free edge of the plate.
An important aspect of this arrangement is that plate 10 extends generally parallel to a tangent to the periphery of the takerin, and is located in a plane which is inclined at an angle to the tangent which is within the range 15.degree. inwardly of the tangent and 30.degree. outwardly when measured from the leading edge 11 of the plate (the terms inwardly and outwardly are used with reference to the centre A of the takerin 4a).
Thus, the angle between the plane of the plate 10 and the tangential plane to the takerin at that region of the takerin which lies closest to the free or leading edge of the plate is not more than 30.degree. where the plate initially diverges from its free edge away from the takerin, and is not more than 15.degree. where the plate initially converges from its free edge towards the takerin. The length d of the plate in the direction of rotation is at least 15 mm, preferably from 22 to 50 mm. The preferred aspect ratio (d/t) of the plate is from 13 to 30, it will be appreciated that the working edge 11 of the plate 10 is in a completely different relationship to the takerin than are the working edges of the mote knives 7, and that the aerodynamic effect of the plate is totally different to that of earlier takerin cleaning arrangements. Surprisingly, it has been found that the arrangement can improve the cleaning efficiency on the takerin by up to some ten per cent, and that the ratio of lint to trash in the undercard droppings below the takerin can be reduced, i.e. more usable fibre is retained.
In a preferred arrangement as shown in FIGS. 2 and 2A, the radial spacing x between the free edge 11 of the plate 10 and the tips of the teeth on the takerin may be from 0.5 to 2.0 mm. the angle .alpha. between the plate and the radial plane A--A is from 90.degree. to 100.degree.. The length d of the plate in the direction of rotation is from 30 to 45 mm, with the plate subtending and angle .beta. at the centre of a takerin of standard 25.4 cm diameter of from 13.degree. to 21.degree.. The angle .gamma. subtended at the centre of the takerin from the nose of the feed plate 2 to the free edge 11 of the plate 10 may preferably be from 30.degree. to 40.degree.. The angle .delta. between the trailing edge of the plate 10 and the leading edge of the takerin screen 8 may preferably be from 10 to 3020 . Each of the aforesaid variables may be determined empirically to suit a given feed stock and set of carding conditions, and it is preferred, therefore, that the mounting bar 12 be supported on the side plates of the carding machine in such a way that it may be adjusted to allow variation of the various angles, and also to allow variation of the spacing between the free edge 11 and the tips of the teeth on the takerin. Suitable adjusting arrangements will readily be apparent. In certain cases it may be possible to eliminate the need for the takerin screen 8.
As well as removing trash, dust and short fibre, which will generally be carried away by the conventional card suction cleaning system, some lint will also be removed by the plate 10, and there is a possibility that removed material may accumulate on the surface of the support bar 12 and in the space between the plate 10 and the screen 13. It will usually be preferred that such accumulation is either constantly or periodically removed, and a suitable method of effecting this would be to mount a blower adjacent to the mounting bar 12 so that a stream of air is directed across the surface thereof in order to blow off accumulated material.
The above description of one preferred embodiment of EP-248649 sets the background to which the present invention can be compared.